Infants with low birthweights often experience health issues both in childhood and in later life. This study demonstrates how certain types of neighborhoods impact the association between maternal age and an infant's birthweight.

Babies born with low birthweight pose a serious public health concern, since weight is an important indicator of a newborn's chances for survival, growth and long-term health. This paper explores the association between neighborhood, maternal age and birthweight by focusing on two characteristics of neighborhoods that may play a key role in infant birthweight outcomes: neighborhood disadvantage and social support.

The researchers collected weight data from Chicago birth certificates (1997–2002) and data on neighborhoods from the Project on Human Development in Chicago Neighborhoods. The sample included 229,613 single births of mothers aged 20–45 years from 342 neighborhood clusters.

Key Findings:

• Almost half of the neighborhoods had a negative association between birthweight and maternal age, which meant that babies born to older mothers were smaller than babies born to younger mothers.
• The remaining neighborhoods had a positive association, which meant that babies born to older mothers were larger than babies born to younger mothers.
• Concentrated poverty was a significant neighborhood-level predictor of the association between birthweight and maternal age.

These results can help public health practitioners to understand the risks present in different neighborhoods and to direct resources accordingly.